avcodec/mjpegdec: bayer and rct are incompatible

Fixes: out of array read
Fixes: 49434/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TIFF_fuzzer-5208501080686592

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/mjpegdec.c

@@ -1092,6 +1092,10 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s, int nb_components, int p
         return AVERROR_INVALIDDATA;
     if (s->v_max != 1 || s->h_max != 1 || !s->lossless)
         return AVERROR_INVALIDDATA;
+    if (s->bayer) {
+        if (s->rct || s->pegasus_rct)
+            return AVERROR_INVALIDDATA;
+    }
 
 
     s->restart_count = s->restart_interval;
@@ -1942,6 +1946,8 @@ static int mjpeg_decode_app(MJpegDecodeContext *s)
         }
 
         len -= 9;
+        if (s->bayer)
+            goto out;
         if (s->got_picture)
             if (rgb != s->rgb || pegasus_rct != s->pegasus_rct) {
                 av_log(s->avctx, AV_LOG_WARNING, "Mismatching LJIF tag\n");